A power cell system with means for detecting a discontinuity

Abstract

A power cell system such as a fuel cell system, with apparatus for detecting a discontinuity. A power cell system, e.g. a fuel cell system, includes a plurality of power cells, e.g. fuel cells and plurality of first resistances, the plurality of power cells and first resistances being connected in the form of a ladder circuit, and electronic filters each having a first connection to a first node between two of the first resistances, each electronic filter having a second resistance and a charge storage device connected to the second resistance.

Description

FIELD OF THE INVENTION[0001]The present invention relates to the field of electrical power cells such as fuel cell or battery systems, and to means for monitoring the power cells and means for detecting a discontinuity in the monitoring means, especially for detecting an open circuit in a wire or cable of the monitoring means.BACKGROUND OF THE INVENTION[0002]Generally DC power supplies such as fuel cells or batteries only have a low voltage difference per cell. This means the batteries or cells are often connected in series in order to obtain a useful working voltage. It is customary to provide some form of monitoring circuit for such a chain or ladder of cells.[0003]A fuel cell is a device, which converts chemical energy into electrical energy, where the functionality is as follows: A fuel on the anode side and an oxidant on the cathode side react in the presence of an electrolyte generating a charge difference between the anode side and the cathode side. An appliance can now be co...

AI Technical Summary

Benefits of technology

[0008]It is an object of the invention to provide a device for use with a power cell system and method of operating a power cell system such as a fuel cell, electrolytic cell or battery system, the device having simple and cheap means for monitoring the cells and for detecting a discontinuity in connections to the cells.

[0011]In one embodiment a power cell system, e.g. a fuel cell system, is provided comprising a plurality of power cells, e.g. fuel cells and plurality of first resistances, the plurality of power cells and first resistances being connected in the form of a ladder circuit, and electronic filters each having a first connection to a first node between two of the first resistances, each electronic filter comprising a second resistance and a charge storage device connected to the second resistance. The resistances may be resistors, a resistor circuit or other types of resistors such as diode connected transistors. The resistances can be connected in a shunt resistor network, In a further embodiment each of the electronic filters is also connected via a second connection to its adjacent electronic filter. The connection of each electronic filter to the adjacent one makes the electronic filters of the fuel cell system work without any separate voltage supplies, because each of the electronic filters is connected to its own power cell, e.g. fuel cell. From this it follows that there is according to each electronic filter only one switch needed, which makes the fuel cell system simpler and cheaper.

[0013]Preferably, each of the electronic filters is a low-pass filter. A low-pass filter has the advantage that it shows no influence on a direct current which is the case for a fuel cell and filters the high frequency portion of voltage changes, which is can be used to perform connectivity checks.

[0014]Each electronic filter is connected to a first or input resistance and since each of the input resistances is a shunt resistor for connection across the corresponding power cell, e.g. fuel cell, and for limiting the output voltage of each power cell, e.g. fuel cell, the fuel cells are never in an open circuit. A permanent electrical current flowing through each fuel cell during operation limits carbon corrosion in PEM fuel cells. One other advantage is that an input resistance helps to detect the discontinuity in the electric power supply.

[0018]Generally, each of the power cells, e.g. fuel cells is for connection with one wire to an input of the corresponding electronic filter, keeping the circuit simple and cheap.

Problems solved by technology

In case of a discontinuity in the electricity supply the applied voltage to the appliance is lowered and therefore the function of the appliance is affected.

Even worse, the fuel may be supplied to a fuel cell even though it is not functioning correctly.

As the fuel is not consumed there is a danger it may be exhausted to the environment.

Since each of the low-pass filters are provided with a separate voltage supply, two switches are needed to charge and discharge the capacitance of the low-pass filters, which makes a connectivity check complex and expensive.

A disadvantage of this embodiment is that only the voltage of a fuel cell portion compared to the ground can be measured and not the voltage of a single fuel cell, which makes it difficult to localize the discontinuity in one of the wires.

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